1. Field of the Invention
The present invention relates to a data communication system having a data reception device that receives at least a portion of data transmitted from a data transmission device via an interface device.
2. Description of the Prior Art
In the past, this type of data communication system employed a relatively simple component such as a buffer or the like as the interface device. However, in recent years manufacturers have given these interface devices a data processing capability by providing them with microcomputers and the like. In this type of data communication system, some data can be processed by only the interface device without the need to transmit that data to the data reception device. Therefore, it is necessary to determine whether data transmitted from the data transmission device should be processed by the interface device or by the data reception device. For example, when firmware or the like that is to be written to a programmable ROM in the interface device is transmitted from the data transmission device, it is necessary to distinguish this data from other data in order to prevent the data from being mistakenly written to the programmable ROM in the data reception device.
One proposal for achieving this objective is to assign an identifier to data transmitted from the data transmission device in order to indicate whether the data should be processed by the interface device or processed by the data reception device. With this configuration, the interface device references that identifier and determines by itself whether to transfer the data to the data reception device or to process the data itself without transferring it to the data reception device. However, the process for assigning an identifier with the data transmission device is relatively troublesome and lowers the processing efficiency of that device.
In view of the foregoing, it is an object of the present invention to provide a data communication system for determining whether data transmitted from the data transmission device should be processed by the interface device or by the data reception device without assigning an identifier to the data.
It is another object of the present invention to provide an interface device and storage medium for achieving this data communication system.
In order to attain these and other objects, the data communication system is provided with a data transmission device for transmitting data, an interface device for receiving data transmitted from the data transmission device, and a data reception device for receiving via the interface device at least a portion of the data transmitted from the data transmission device. The data transmission device is provided with determining means for determining whether the transmitted data is data to be processed by the interface device or data to be processed by the reception device; and a data transmitting device for transmitting, based on the results of the determination, data to be processed by the interface device using a first communication protocol and data to be processed by the data reception device using a second communication protocol different from the first communication protocol. The interface device is provided with data processing means for processing data transmitted from the data transmission device by the first communication protocol rather than transferring the data to the data reception device; and data transferring means for transferring data to the data reception device when the data is transmitted from the data transmission device by the second communication protocol.
In a data communication system of this construction, the determining means of the data transmission device determines whether data to be transmitted by the data communication device should be processed by the interface device or the data reception device. Based on the results of this determination, the data transmitting means of the data transmission device transmits data to be processed by the interface device using the first communication protocol and data to be processed by the data reception device using the second communication protocol different.
When data is transmitted from the data transmission device using the first communication protocol, the data processing means in the interface device processes the data without sending it to the data reception device. When data is transmitted from the data transmission device using the second communication protocol, the data transferring means transfers that data to the data reception device.
Therefore, the interface device of the present invention determines, based on the communication protocol in association with the data, whether to transfer the data received from the data transmission device to the data reception device or to process the data itself without transferring the data to the data reception device. Hence, in the present invention it is possible to determine whether data should be processed by the interface device or by the data reception device without the need to assign additional data (for example, identifiers) to the transmitted data for the purpose of making this determination. Accordingly, the present invention not only simplifies processing in the data transmission device and improves processing speed, but also simplifies the construction of the data transmission device, thereby reducing production costs.
According to another aspect of the present invention, each of the interface device and data reception device is further provided with a programmable ROM that includes a rewritable storage area: a CPU for executing processes based on processing programs stored in the storage area; and a RAM for temporarily storing data necessary for such CPU processes. Data transmitted using the first communication protocol and the second communication protocol include new processing programs to be written to the programmable ROM in either the interface device or the data reception device.
By writing a new processing program to the programmable ROM of the interface device and data reception device of the present invention, it is possible to improve the functions of both. However, if processing programs intended to be written to the programmable ROM of the interface device are mistakenly written to the programmable ROM of the data reception device, or processing programs intended to be written to the programmable ROM of the data reception device are mistakenly written to the programmable ROM of the interface device, the respective devices will not operate properly and will hinder proper functioning of the entire communication system.
To prevent this from happening in the present invention, new processing programs to be written to programmable ROM can be reliably directed according to the configuration described above. Accordingly, not only are the effects of the invention described more remarkable, but also we can see new effects, such as the capability to satisfactorily prevent the occurrence of mistaken operations in the interface device and the data reception device.
According to another aspect of the present invention, the data reception device is provided with an image forming device for forming an image on a recording medium based on image data received via the interface device. The second communication protocol is the same communication protocol used when transmitting image data to the data reception device.
As a result, the data receiving device of the present invention is capable of forming an image on a recording medium according to the image forming device based on image data received via the interface device. Further, in the present invention the second communication protocol is the same protocol used when the data reception device receives image data. For this reason, the interface device can direct data by transferring data received using the second transmission to the data reception device, regardless of the type of data.
Therefore, it is not only possible to simplify the process and construction of the interface device and further improve the processing speed, but also to reduce production costs.
According to another aspect of the present invention, when the data is a new processing program to be written to programmable ROM in either the interface device or the data reception device, the data transmission device assigns a password to the new processing program before transmitting the data. The interface device or data reception device writes the new processing program to the associated programmable ROM only when such a password has been assigned to the data.
As a result, it is possible to sufficiently prevent data for an undesirable processing program or data other than a processing program to be written to the programmable ROM as a new processing program. Hence, it is possible to more adequately prevent a processing program intended for another device to be mistakenly written to the ROM device. Accordingly, reliability of the communication system can be further improved.
According to another aspect of the present invention, either the first communication protocol or the second communication protocol is either TFTP or LPR and the password described above is written in place of the pathname data for the transmission source file.
Accordingly, a more simplified data system can be achieved by simply writing the password in place of the pathname of the transmission source file. Therefore, in addition to the effects described above, it is possible to further simplify the construction of the communication system and increase reliability.
According to another aspect of the present invention, the interface device is connected to a communication line and transfers data received from the communication line to the data reception device. The interface device is further provided with data processing means for processing data received from the communication line by the first communication protocol without transferring that data to the data reception device; and data transferring means for transferring data to the data reception device when such data is received from the communication line by the second communication protocol different from the first communication protocol.
In other words, the interface device is provided with data processing means and data transferring means. For this reason, the data communication system can be of a simple construction, wherein the data reception device is connected via the interface device to a communication line through which data is transmitted from the data transmission device. A communication system of this construction has the same effects as those described above.
According to further aspect of the present invention, a recording medium which stores computer programs for controlling the data transmission device. The computer programs stored in the storage medium include a determining program for determining whether the transmitted data is data to be processed by the interface device or data to be processed by the data reception device; and a data transmitting program for transmitting based on the results of determination data to be processed by the interface device using a first communication protocol and data to be processed by the data reception device using a second communication protocol different from the first communication protocol.